The Effect of Lightweight Expanded Clay Aggregate on the Mitigation of Liquefaction in Shaking Table
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ORIGINAL PAPER
The Effect of Lightweight Expanded Clay Aggregate on the Mitigation of Liquefaction in Shaking Table Ali Ghorbani
. Hakimeh Rabanifar
Received: 26 December 2018 / Accepted: 30 September 2020 Ó Springer Nature Switzerland AG 2020
Abstract Non-conventional materials are often applied to dissipate the energy of dynamic loads and mitigate liquefaction. In this study, the effect of Lightweight Expanded Clay Aggregate (LECA) on the mitigation of liquefaction was examined using shaking table tests. LECA, a common lightweight material, was added to saturated sand in a range of 0–20% to study the variation of excess pore water pressure (EPWP) generation, as well as the acceleration response of the soil. Based on the obtained results, the addition of 5% and 10% LECA to saturated sand resulted in a significant decrease in the generation of EPWP, while higher LECA content led to an increase in the generation of EPWP. The mechanisms behind such behaviors contradict the effects of increasing the damping of the soil mixture and reducing the effective initial stress as a function of overall mixture density. Adding 5 and 10% LECA reduces EPWP because aggregates accelerate the dissipation of EPWP during and after vibration. As the percentage of LECA increases by 15% and 20%, excess pore pressure ratio increases. The cause of this may be the reduction of effective initial stress leading to reduced soil density in higher-LECA contents. 10% LECA is presented as the threshold for changing the liquefaction behavior of sand-LECA mixtures. This study concludes that A. Ghorbani (&) H. Rabanifar Dept of Civil Eng, Faculty of Engineering, University of Guilan, Rasht, Iran e-mail: [email protected]
adding LECA to sand samples increases the rate of dissipation of EPWP, but also leads to a significant decrease in initial effective stress. Keywords Sand Lightweight expanded clay aggregate (LECA) Liquefaction Shake table test Pore pressure
1 Introduction Earthquake-induced ground vibrations facilitate the process of building up EPWP. As EPWP increases in saturated sand, effective vertical stress decreases and tends toward zero. This phenomenon is known as liquefaction, which causes major consequences to surface structures and subsurface utility lines. Liquefaction occurs due to a rise in EPWP and a resulting decrease in the effective overburden stress in soil. Many soil improvement strategies have been employed over the years to reduce or eliminate the consequences of liquefaction, typically using trial and error to determine the best methods. Traditional mitigation techniques, though widely used, pose various problems, including negative environmental effects, disturbances to existing systems, size of the area to be dealt with, etc. Gravel drains (Bouckovalas et al., 2009; Papadimitriou et al. 2007), stone columns (Huang et al. 2015; Maduro et al. 2004), stone column
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Geotech Geol Eng
encased with geosynthetics (Tang et al. 2015), and vertical drains with vario
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